DESCRIPTION: Early childhood caries is a disease of epidemic proportions in ethnic minority communities. The caries rate for hispanic children in early and later childhood is very high and existing treatment for early childhood caries is ineffective. There is strong evidence that fluoride varnish reduces caries progression in Scandinavian children aged 3-6 years. However, the application regimens reported by these investigators still produced unacceptably high caries progression rates. More intensive application regimens, i.e., three times a week, have been tested with older Scandinavian children and have been found to reduce caries. The proposed trial, building on previous pilot work, is to establish the most effective application rate and interval for maximal cariostatic activity in high caries risk preschool children. The specific aims of the research are: 1) to use a double-blind, placebo controlled design to determine the efficacy of three application regimens of 50 milligrams NaF/ml fluoride varnish (Duraflor, Pharmascience) in preventing dental caries progression in 156 Mexican-American children aged 36-60 months. One application semi-annually will be compared to three annual and semi-annual applications; and 2) to describe the characteristics of children with and without caries progression. The primary dependent measure in the study will be the progression of proximal lesions detected by radiography. The study will be conducted at Headstart Centers in the Yakima Valley of Washington State.